Elevator machine



May 30, 1933. Q R PRATT 1,911,389

ELEVATOR MACHINE Filed Oct. 7, 1930 2 Sheets-Sheet l INVENTORIS.

\% AZa MMM A TTORNEYS.

May 30, 1933. R, PRATT 1,911,389

ELEVATOR MACHINE Filed Oct. 7, .1930 2 Sheets-Sheet 2 .fi. 2;; S l3 8 I I H w ATTORNEYS.

Patented May 30, 1933 UNITE STATES- CHARLES R. PRATT, OF UPPER MONTCLAIR, NEW JERSEY ELEVATOR MACHINE Application filed October 7, 1930. Serial No. 483,953.

This invention relates to an improvement in elevator systems, and has for one of its objects the provision of a machine which is more flexible than prior machines and which possesses all of the refinements of speed control of a direct current variable voltage clevator system.

A further objectof the invention is the provision of a construction employing two driving motors for the car, both of which are employed in normal running at full speed, but each of which is capable of operating the car at reduced speed in the event of failure of the other motor. hus the pres ent invention presents a distinct advantage over variable voltage elevator systems, for example, wherein failure of any one of the three units empioyed interrupts service until repairs are made, which may be a matter of hours.

Briefly the invention comprises a construction embodying two single speed alternating current driving motors so connected to the cable drum that the machine may be constructed and operated at less cost of installation and operation than a hoisting machine for equal service and employing a single twospeed alternating current motor.

More specifically the present construction embodies a pair oi single speed alternating current motors both of which are employed in. driving the elevator car at normal speed but either of which is adapted through diii'erential mechanism to drive the car alone but of course atreduced speed, both motors running in the same direction and at full speed to drive the car at full speed. The driving motors are duplicates of each other, but the differential gear ratio between one motor and the cable drum differs "from that between theother mot-or and the cable drum. This makes the machine very flexible as to speed control in that it permits of the car being run at a very slow speed in either direction simply by rotating the motors in opposite directions. This is vastly superior to prior two'speed machines, such machines requiring two motors each of a different speed and each of full horse power. In other words, the total horse power required in such machines is twice the motor horse power required to drive the elevator, while the slow speed is one-third to one-sixth full speed, which is altogether toofast for automatic precision. floor leveling except when dealing 5 with slow speed elevators.

In the eievator industry the only cause for serious interruption in elevator service is failure of he hoisting motor or the hoisting mechanism, and by eliminating this possibility by providing for driving the car with e ther motor alone, as above pointed out, there remains only failure of control circuits to take into consideration, a matter of minutes to take care of.

Speeds of more than three hundred feet per minute in high class passenger elevator servlce are at presentobtained by the use of voltage type of machine. ine apparatus or this invention can be 1nstalied for about one half the cost of a variable voltage installation and will operate 6 1 es newer. Furthermore, the pres- 58 gives better service in auto- 1 stops, in that it provides for a si'ower positive leveling speed than a gearless variabie voltage type of elevator. Ac-

tion is smoother with the machine of :ention in that the driving motors in starting operated in reverse directions and the car will not start until the relative; load torque of the two motors gives them their r ilative speed to drive the car at its slow leveling speed. At that moment the reve sed motor slows down and stops, reverses and then accelerates to full speed, following the other motor until the car is driven at full speec In decelerating or coming to rest the cycle is the same except in reverse sequence, with an additional refinement provided by the brake mechanism and which will be described hereinafter.

In the accompanying drawings wherein an embodiment of the invention is shown: Fig. 1 is a plan view of the machine; Fig. 2 a section on the line 22 of Fig. 1; Fig. 3 a section taken on the line 3-3 of Fig. 2; and

Fig. i a wiring diagram of a controller and 2 suitable for use in connection with the a pparatus of the other ligures of the drawings.

Referring to the drawings in detail, the improved machine of this invention comprises in general a pair of single speed alternating current electric driving motors designated 1 and 2, respectively, the motor 1 being coupled to a worm shaft 3, while the motor 2 is coupled to worm shaft 4.

5 designates a gear housing containing the planetary gearing shown in Fig. 2 and in Fig. 3, while 6 designates the cable drum to be driven.

From an inspection of Fig. 2 it will be seen that 7 designates a supporting shaft extending the length of the gear housing or gear case 5. Mounted on a tubular driving member or sleeve 8 which is provided adjacent one end of the shaft 7 and which sleeve rotates on roller bearings 6 is the cable drum 6 above referred to.

Mounted on ball bearings 12 at the opposite end of the shaft 7 is a hollow driving shaft or sleeve 9 flanged at. its outer end as shown at 10 and having a worm gear 11 bolted thereto.

The worm gear 11 is driven by the motor 1 through the drive shaft 3 which is provided with a worm 1-) for this purpose. For the purpose of clarity of description the motor 1 will be referred to hereinafter as the fast motor.

Bolted to the inner end of the hollow shaft 9 by bolts 14: is an externally toothed spur gear 15. Meshing with this gear are a plurality of planetarypinionslli. Each of these pinions is mounted on a pin 17 carried in two plates 18-18 spaced by thimbles 19 and bolted together and to the inner end of the sleeve 8 by bolts 20.

Surrcnmding the planetary pinions 16 is a gear member 21 which is bolted to a tubular driving member or sleeve surroimding the tubular driving member 9 already referred to. This member 22 is mounted on the member 9 on ball bearings :23 at one end, the other end being mounted directly on the member 9. a wearing ring being provided intermediate the sleeves.

The gear member Q1 is provided intcrnallv with spur gear teeth ill meshing with the pinions 1(3, and externally with worm gear teeth 25 meshing with the worm L5 on the shaft 1 of the motor 2.

The g ar ratio between the motor 1 and worm gear 11 as compared with the gear ratio between the motor 2 and worm gear 21 is such that the motor 1 will drive the drum 6 faster than the motor The motor 1 already having been referred to as the fast motor, motor 2 will be referred to for the sake of clarity as the slow motor.

It will be obvious that when both motors 1 are running in the same direction the cable drum 6 will be driven through the gearing above described a t full speed.

It will equally be obvious that when one motor alone is running the car will be driven at a slower speed depending upon the gear ratio between the particular motor running at the moment and its worm gear. It will be appreciated also that with both motors running but in opposite directions the car will be driven at even a lower speed than when driven by one motor alone.

This provides, therefore, a construction in which the drum 6 may be driven in either direction by either of the driving motors 1 and 2 but at very much reduced speed, but while this is a fact nevertheless such construction is superior to prior constructions wherein failure of one of the motors of the several employed necessitate shut down of ole ator service until the motor is repaired.

It will be seen also that this construction provides for driving the car, in making a landing, at an extremely slow speed which will permit of precision floor leveling inasmuch as in making a landing the motors will be driven in opposite directii'ins and the resultant landing speed may be reduced to any point desired simply by proper design of the gear ratios between the driving motors and their respective worm gea The fast motor 1 is provided with lJlftllU! mechanism 2b and slow motor 2 with brake me hanism 27. 2S designates the springs for the brake 2b, the bra he being spring-applied as is customary in elevator installations, and designates the springs of the brake 27. In installing this appa atus the brute springs 28 of the fast inotorarc set so as to apply the brake 2b slightly harder than the application of the brake 27 with the result that in ln'inging the apparatus to rest the brake 26 will slow down the motor 1 to a point, by proper adjustment of the springs .28, where the speed of the elevator will have been reduced almost to zero at the instant the brakes are applied to stop the elevator.

Fig. lis a wiring diagram of a controller suitable for use in connection with the apparatus above described. Referring to this drawing, 30 and 5:31 designate, respectively, the up and down reversing switches for the slow motor 2, while 32 and 333 designate, respectively, the up and down reversing switches for the fast motor 1. 3+1; designates the car switch. If the car switch is moved to the right. as viewed in Fig. 4;. from its full line position to the first dotted line position which has been designated 35 a circuit will be closed to the up switch 32 of the fast motor 1, which circuit may be traced from one side of the line through the switch lever 34, contact 36. conductors 37 and 38, through the up switch 32 to the other side of the line.

lVhen the up switch 32 pulls in a circuit will be closed to the fast motor 1 including the coil B of the brake operating magnet for the brake 26 for this motor as well as a circuit to the down switch 31 of the slow motor 2. The circuit of the down switch 31 may be traced from one side of the line, switch lever 34, contact 39, conductor 40, contacts 41, 4:2, conductor 13, switch 31, to the other side of the line. The closure of the switch 31 will follow the closure of the switch 32 with a consequent lag in the closure of the armature circuit for the slow motor 2 as compared to the closure of thearmature circuit of the fast motor 1, the closing of the up switch 32 immediately closing the circuit to the motor 1 whereas the down circuit of the slow motor 2 does not close until after the down switch 31 has pulled in. It is tobe understood that the closure of the circuit of the slow motor 2 also effects a closure of the circuit of the coil C of the brake operating magnet for the brake 27 for the motor 2.

Through the differential mechanism above described it will be appreciated that the drum 6 will now start in rotation with the motors 1 and 2 running in opposite directions and due to this and the difference in the gear ratio between the motors and the drum 6 it will be appreciated that the car will be started at very slow speed.

Further movement of the switch 34 to a position where it rides off the contact 39 maintains the circuit of the up switch 32 of the fast motor 1 closed but opens the circuit just traced to the down switch 31 of the slow motor Consequently the drum 6 will now be driven by the fast motor 1 only but still at a reduced speed. Continued movement of the .switc 1 3f to the dotted line position designated 1%, so ,o engage the contact 15, will close a circuit to the winding of a dashpot switch 46 which is equipped with a dashpot 16. This circuit may be traced from one side of the line. through the switch lever, contact 1-5 conductor 47, winding of switch 46, to the other side of the line. When this switch pulls in a circuit will be closed to the up switch 30 of the slow motor 2. This circuit may be traced from one side of the line, switch lever 34, contact 36. conductors 37, 48. contacts 4:9 and 50 of: the switch 46, conductor 51. winding of the up switch 30 of the slow motor 2 to the other side of the line. WVe now have a condition where both of the motors 1 and 2 are running in the same direction and the drum 6 ti veling at maximum speed.

In coming to rest reverse operation is effected merely by moving the lever 34; to central or neutral position, the movement of this lover of the contact 45 opening the circuit of the winding); of the dashpot switch 46 so that the circuit of the up switch 30 of the motor 2 is open, the car then being driven by the 1notor 1. As soon as the car lever has been moved on the contact 39 a circuit is closed to the down switch 31 of the slow motor 2 so that this fast motor is then opposing the mo tor 1 with aconsequent further reduction in speed of the drum 6.

When the ear switch. moves olf the contact 36- the circuit to the winding of the up switch 32 of the fast motor 1 is instantly opened and when'this switch has dropped the circuit of 'the'fast motor 1. is opened. The open ng of theswitch 35) at the contacts 41 and 2, which takes place simultaneously with the opening of themotor circuit 1, opens the circuit to the down switch 31 of the slow motor 2. The opening of the switch 31, due to the winding thereof being deenergized will, as will be appreciated, lag behind the opening of the circuit of the motor 1 so that there is a distinct time interval between the opening of the circuit of the fast motor 1 due to the opening of the switch 32 and the opening of the circuit of the slow motor 2 due to opening of the switch 31. that this time lag will effect a further reduction in the car speed so as to bring the car to rest with a smooth action.

In service the fast motor 1 may drive the ear 'for example 10% faster than the slow motor 2 and the time between the opening of the circuit of the fast motor 1 and the open in g of the circuit of the slow motor 2, due to the lag of the magnet 3h is sutlicient to allow the fast motor 1 to decelerate to of its full speed. e have therefore, a condition where the fast motor 1 is running 90% speed and the slow motor 2 running at full n -cell th... waging; the sheave 6 to in 10% the travel that would. occur were rest both motors decelerated simultaneously.

As previously mentioned the brake springs iusted so that their pressure upon 0: i .otor 1 will be greai'jer than that the brake. 2'? onthe motor 2 and as the b *akes areapplied which will be the lever is moved on to the contact 39 and oil conact 36 toward neutral position the brake action on the motor 1 is stronger than thaton the motor 2 so that the difference in speed at which the motor 1 is tending: to drive the drum 6 in one direction and the motor 2 in the otherdirection will be further reduced to st' further reduce he speed of the drum (3, win the result that when the brakes are finally applied to stop the drum the speed of "rum has been reduced almost to Zero.

It will be seen from the ra'cgtdng, therefore. that the present invent oirprovides an elevator machine in which two motors are employed to drive the cable drum, either of lure motors being capable of driving the drum alone but at reduced speed, therel'iy providing. for emergencies in operation of the elevator such as failure of one of the motors.

It will be seen also that differential mechanism is provided between each of the motors and the cable drum, the gear ratio of the connection of one motor to the drum being different from that of the other motor to the drum, so that in starting up or slowing down, atwhich time the motors are driven in opposite directions. the drum is caused to accelerate 5 r to decelerate very gradually and smoothly and at the inf-tantof start or stopping the speed of the drum is almost zero. Of course this a rran gemcnt permits of not only smooth.

7 starting but accurate leveling of the car at 10 floor landings.

It will he understood that changes may be made in the details of construction above described without departing from the spirit and scope of this invention.

What claimed is:

1. in elevator machine comprising in combination a supporting shaft, 21- sleeie mounted for rotation thereon, a cable drum afiixed to isaid sleeve. planetary pinions tarried by said sleeve, a second sleeve on said shaft concentric with the mentioned sleeve, an externally toothed gear carried thereby, and meshing with said pinions, a third sleeve on said shaft, a gear member attached thereto and provided 25 with internal teeth meshing with said pinions, worm gear teeth on the exterior of said gear member, a worm meshing with said Worm gear teeth, a motor for driving said worm, a. worm gear attached to the second mentioned s eeve. and a second motor for driving said last iii-enticnerl worm gear.

An elevator machine comprising in combination a cable drum, a pair of electric driving motors thrretor, differential mechanism connecti11 said motors to said drum, and controlling me hanism for effecting rotation oi said motors in opposite directions in bringing the cable drum to rest, said controlling mechanism comprising a reversing switch for each motor. one of said switches controlling the circuit of the other switch whereby there will he a time lag between the opening of the circuits of said motors.

3. An elevator machine comprising in comhination a cable drum, and a pair of electric driving motors dificrentially geared to said dram at ditiercnt ratios. means for effecting rotation of said motors in opposite directions to drive the drum at slow speed, means for opening the circuit of one motor while holding the circuit oi the other motor closed to dri e the drum at a speed in excess of said slow speed. means for effecting rotation of said motors in the same direction to drive the drum at 'tnll speed. and means to start and to dcceleratc the taster geared motor ahead of the slower geared motor.

This specification signed this 3rd day of C'ctobcr, 1930.

50 CHARLES R. PRATT. 

